"Political correctness (adjectivally politically correct, both forms commonly abbreviated to PC) is a term used to describe language, ideas, policies, or behaviour seen as seeking to minimize offence to racial, cultural, or other identity groups. Conversely, the term politically incorrect is used to refer to language or ideas that may cause offense or that are unconstrained by orthodoxy. The term itself and its usage are hotly contested. The term "political correctness" is used almost exclusively in a pejorative sense. Those who use the term in a critical fashion often express a concern that public discourse, academia, and the sciences have been dominated by excessive liberal viewpoints. Some commentators, usually on the political left, have argued that the term "political correctness" is a straw man invented by the New Right to discredit progressive social change, especially around issues of race and gender. The term can also be used to describe any form of political orthodoxy whether the orthodoxy is from the left or the right.." "The often quoted earliest cited usage of the term (in the form "not politically correct") comes from the U.S. Supreme Court decision Chisholm v. Georgia (1793), where it clearly means that the statement it refers to is not literally correct, owing to the political status of the United States as it was understood at that time. The term "political correctness" is derived from Marxist-Leninist vocabulary, and was used to describe the appropriate "party line", commonly referred to as the "correct line" Those people who opposed (or were seen as opposing) the "correct line" were often punished. The term was used in communist countries, and by communist and Trotskyist parties. It was then adopted in several related meanings by some in the U.S. political Left." "Within a few years, however, the term "political correctness" had been re-appropriated within the U.S. political left as a satirical form of criticism of ideas seen as too doctrinaire and rigid." Source and further information: http://en.wikipedia.org/wiki/Politically_correct

Well it started in communist countries to denote people and behavior that did not conform to the "party line" - did not behave in ways that the government had published as best for the country. In the U.S. it developed in response and opposition to attempts by Marxist thinkers to recast moral, political, and ethical behavior by artificially imposing a "class" system of "haves" and "have-nots" or "victims" and "victimizers" upon society in order to utilize totalitarian means to suppress individuality and freedom and thus "level" society. So being "politically correct" meant blindly and without consideration or questioning following the "party line" of those who would sabotage the individual freedom and personal accountability afforded by a democracy.